Lying

The benefits of telling the truth far outweigh the cost of lies—to yourself, to others, and to society.
Failures of personal integrity, once revealed, are rarely forgotten. We can apologize, of course. And we can resolve to be more forthright in the future. But we cannot erase the bad impression we have left in the minds of other people.
In many cases, false encouragement can harm the other person. Telling a fat person they’re thin, telling a bad writer they’re doing great, telling a sloppy mess that they’re attractive, these all hold them back from fixing their problems. We do it because we’re scared of hurting their feelings, but we do more damage in the long run.
The solution isn’t to be an asshole, but to find ways to provide the truth objectively.
If your friends know you will be the one to tell them the truth, they’ll come to you more. You’ll be a welcome change because they know you won’t just coddle them.
Knowing that we will attempt to tell the truth, whatever the circumstances, leaves us with little to prepare for. We can simply be ourselves.
A commitment to honesty does not necessarily require that we disclose facts about ourselves that we would prefer to keep private.
If you think that it can ever be appropriate to injure or kill a person in self-defence, or in defence of another, it makes no sense to rule out lying in the same circumstances.